In recent years, regulations are increasingly strengthened on a biological test and a clinical test conducted for the sake of treatment of human diseases. As an alternative for the biological test and the clinical test, research and development have been extensively made on the collection of live cells from the human blood. The collection of cells is conducted by different kinds of cell collecting devices such as a micro-fluidic device, a CTC (Circulating Tumor Cell) chip, a filter, and so forth.
As one example of the cell collecting device, U.S. Patent Publication No. 2007/0025883A1 discloses a parylene membrane filter for filtering cells from fluid. The membrane filter is installed within a chamber and is provided with a plurality of pores formed to deter passage of cells, e.g., cancer cells.
As another example of the cell collecting device, U.S. Patent Publication No. 2009/0188864A1 discloses a method and apparatus for microfiltration to perform cell separation. A plurality of filter patches is installed in the central square hole of the microfiltration apparatus. Each of the filter patches is formed of a membrane having a plurality of pores for filtering cells. In the technologies of U.S. Patent Publication Nos. 2007/0025883A1 and 2009/0188864A1, the cancer cells filtered by the filter are recovered and collected by supplying a solution, e.g., water, into a chamber in a backward direction and forcibly discharging the cancer cells out of the chamber. This poses a problem in that it is quite difficult to recover and collect the cancer cells from the filter. Another problem lies in that the cancer cells are easily damaged in the process of discharging the cancer cells from the chamber.